apparently, it's all rooted in science. your dog or your cat may be depressed. and the treatment that works for humans may work for your pets. it's true. abc's dan harris has the story. >> reporter: of all the absurd things we do for our pets, the massages, the themed birthday parties, the treadmills, the high-end couture. the paris hilton dog house. >> inside is moldings and lighting and heat and air conditioning. >> reporter: of all of the over-the-top pampering, this picture, struck me as the apex of this particular brand of mania. this doe-eyed little pooch is staring into an artificial sunlight generator, in case he's getting depressed from lack of sun exposure. it's made by a company called max lighting. then, i heard of the inventor. max's doctor told him to use a bright box to counter the gloomy days. it worked. not only on max, but on his golden retriever, luke. >> luke and i were basking in the sun. and he was drawn to the light. >> reporter: max did research. and a lot of vets say pets may be getting seasonal affective disorder. a condition that cause